TTC&Macrolide PPT.pptxTTC&Macrolide PPT.pptxTTC&Macrolide PPT.pptxTTC&Macrolide PPT.pptxTTC&Macrolide PPT.pptx

1. Mixed Case
(TTCs & Macrolides)

2. Case 3
R.M, a 7 years old child with medical history of gastric hyperacidity, came to hospital suffering
from productive cough with greenish sputum, shortness of breath, high temperature and feeling
generally unwell over several days. Blood and sputum cultures yielded streptococcus
pneumoniae (gram positive bacteria). So, the physician prescribed an oral antibiotic and
painkillers along with rest and drinking plenty of water.
A. Tetracycline B. Azithromycin C. Erythromycin
D. Doxycycline E. Chlortetracycline F. Erythromycin Estolate

3. Question 1:
1. Predict the drug of choice in this case with justification.
The correct answer is:
Drug no B- azithromycin
Justification:
1 Removal of 9-keto group coupled with incorporation of tertiary amine
nitrogen function into macrolide ring increases the stability of
azithromycin against acid catalyzed degradation and making it suitable in
this case with history of gastric hyperacidity over erythromycin and its
prodrug estolate.
2 All tetracyclines are contraindicated in this case (child younger than 8
years) due to high affinity of tetracyclines for calcium causes them to be
incorporated into newly forming bones and teeth.

4. Question2:
2. What advise should you give about taking this oral antibiotic?
The correct answer:
Azithromycin is associated with food-drug interaction: maximum absorption
occur when taken on empty stomach so must be taken before diet by 1-2 hr
once daily for 3-5 days as if taken with food: its absorption decrease to 40-
50%.
Question3:
3. What is the role of encircled group in the drug D?
The correct answer:
5-OH group (oxytetracycline, doxycycline) improve the pharmacokinetic
properties without affecting the anti-microbial activity.

5. Question4:
4.Drug no E (Chlortetracycline) is associated with a special toxic effect
explain.
The correct answer:
Tetracyclines with a C-7- chlorine absorb light in the visible region leading to free
radical generation and potentially causing severe erythema on exposure to strong
sunlight (additional Cl on C7 ↑ activity than tetracycline but ↑ photosensitivity).